Sound-absorbing panel



March 1954 c. BOURGEOIS 2,671,522 I SOUND-ABSORBING PANEL Filed March 31,1950 2 Sheets-Sheet l (hm/es Boucqe0L3jl/YVf/YTOR PER: MLW

March 1954 c. BOURGEOIS 71,52

SOUND-ABSORBING PANEL Filed March 51, 1950 Y 2 ShGGLS-ShGGt 2 III-I...-

Charl s Bourgeois,

l/YVfl/TOI? .4 TTOR/YEYJ Patented Mar. 9, 1954 UNITED STATES PATENT OFFICE 1 Claim.

The invention has for its object panels and, more generally partitions or coatings for partitions, adapted in such a way as practically to absorb all sound vibrations that strike them.

It is known that to obtain that end it is necessary on the one hand to adapt the panels in such a way as to avoid the vibrations peculiar to their elements and, on the other hand, to prevent refraction.

With this object in view various forms of embodiment have been proposed for the realization of which different materials, generally of a fibrous kind, such as spun glass, wood wool, panels of compressed wood, have been used.

It has already been proposed to pierce in those panels apertures that traverse them wholly or partially. Nevertheless every attempt has until the present resulted only in a partial success, and even if it is true that a percentage, even an important percentage of the sound vibrations have been absorbed, it is equally true that the results achieved do not answer the requirements of the technique of today.

The applicant has observed that it is not enough to make use of materials not themselves absorbent, but that the materials should at the same time offer a considerable absorbent surface and a profile capable of damping the sound vibration which might still be reflected owing to the fact that the free surface of the material must, in any case, have a certain decorative appearance detrimental to the absorbing capacity of the material.

According to this invention, panels with a considerable or an almost total power of absorption are produced by using a slab of a compressed fibrous matter, for example cellulose fibre and more commonly wood fibre, and by making in the outward surface of this slab grooves in two series, in which all the grooves of one series are parallel or nearly parallel to one another and the two sets of grooves are perpendicular or almost perpendicular to one another.

The groove of one set are of the same or of different depths, just as the depth of all or of one part of the grooves of one set is equal to or different from the grooves of the other.

Owing to this general arrangement, the panel, takes as it were, the shape of a common support fora great number of small prisms slightly separated from one "another, each prism being entirely surrounded by other prisms, except of course, those along the side of the panel.

Such panels can also form the large faces of flat casings filled or not with sound-absorbing matter.

Owing to this characteristic arrangement, the absorbent surface is not only greatly increased, but an extremely dense net of channels or grooves is created, whereby the vibration of sounds striking the panels is damped.

It must also be noted that the absorbing surfaces due to the grooves-the distinguishing feature of the invention-are or may be much more eificient than the apparent surface of the panel, which surface should be treated in such a manner as to appear more even or to present an ornamental appearance, the partitions bordering the grooves remaining as they were.

Therefore from the illustration of Fig. 1 at: tached hereto, which shows one of the absorbing prisms seen in perspective View it will be remarked that each prism presents not one free surface but four lateral surfaces 2, and that these lateral surfaces are even more absorbent than the said free surface, as has just been demonstrated.

The absorbent materials could of course, be produced by all the suitable processes and machines and the bounds of the absorbent prisms could therefore result from the application of various methods, such as casting compressing, sawing, moulding, etc.

By way of example a few of the effects produced are shown in the attached drawings, in which:

Figure 2 presents in perspective view a panel produced according to the invention.

Figures 3 and 4 represent elevations of modified forms of embodiment of said panel; 7

Figures 5 and 6 show two perspective views with partial section of other modified forms of embodiment;

Figures 7 to 13 show partial elevations of different modified forms of embodiment of said panels;

Figure 14 shows in section the construction of resilient panels;

Figure 15 represents in partial perspective View another modified form of embodiment of the panel according to the invention;

Figure 16 represents in perspective view and in partial section, a panel produced in the shape of a casing;

Figure 1'7 gives a perspective view of an application of the panel, object of the invention.

From these different diagrams it is seen that a panel produced according to the invention is generally speaking, formed by a slab 3 of some relatively solid material serving as a kind of support for the small absorbent masses 4. Such absorbent masses vary considerably according to the shape they present in plan view and according to the shape and depth of the grooves bounding the same.

In Figure 2 the panel according to the invention is produced from a base slab 3, in which grooves divided according to two bundles 5 and '6 of parallel grooves, are made. In this way the absorbent prisms 4 are automatically fixed and are all equal. The grooves extend partly through the panel and alternate ones of said grooves have a depth greater than that of adjacent rooves.

In consequence, quite a number of forms of embodiment may be obtained by changing the arrangements of the grooves 6. Figure 3 illustrates different arrangements of two bundles of parallel grooves. In all these cases absorbent prisms 4 are obtained, but the shape and the disposition in relation to the base slab 3 are different.

Another series of forms of. embodiment may be obtained not by using the networks of parallel grooves, but by making grooves of variousshapes.

Figure 4 shows, by way of example small absorbent masses 4 enclosed by circular grooves l in the upper part, and small prismatic absorbent masses on anhexagonal basis in the lower part. Anyshape may be given'to the grooves, geometrical and others, with really artistic results according as the contours are marked by grooves of a regular or an irregular depth. Inthe latter case, the small absorbent masses would, of course, be replaced by-unequal masses of an essential variable form.

Thus by varying the arrangement of the grooves an almost endless range of absorbent panels according to the invention may be obtained.

Still other variations may be achieved by altering the shape and depth. of the grooves themselves.

Figure 5 shows a panel 3, of which the parallel grooves 5- are all of the same depth and the grooves 6 are also all of the same depth, which depth differs from that of thefirst panels 5. On the other hand, in the example of Figure .6, the grooves of the two parallel networks 5-6 are of unequal depth and in this case a groove of greater depth alternates with one of smaller depth.

The variation in the depth of the grooves will be determined by the effect it is desired to produce. In fact it has been demonstrated that deep sounds were in the case of a certain depth of groove, absorbed better than shrill sounds, and vice versa. By adapting the depth of the grooves tov the proportion of the sounds to be damped, a really maximum result may be obtained.

Of course thearrangements which affect the characteristics of the absorbent masses and of the grooves which enclose them, make it possible to treat the two faces of a panel in the same or in a different manner; see diagrams l and 8.

.Still. other. .forms of embodiment may result from the shape given to the verticalsections of the grooves. By this shape that of the twolateral faces of the small absorbent masses will natural-'- ly be determined. These grooves may be trapezoidal, as is Figures 9 and 10, or circular, as in Figure 11.

The absorbent panels according to the invention and having one or more of thecharacteristics previously described may be applied as they are or in different combinations according to the need.

' In Figure 12 is seen such an absorbent panel 3 glued to a solid panel 8, which may be made of a material similar to or different from those of which the absorbent panel is composed.

Figure 13 illustrates the combination of such an absorbent panel 3 and a solid panel 8,but with an empty space 9 between them, the panels being held innplace by partition laths l0. .A similar arrangement may moreover be achievedby using two absorbent panels 3' separated by an empty space 9. In exceptional cases, it may be desirable to have flexible panels for the covering of a curved face. Thus, a resilient support 3 as shown in Figure 14, may be employed, and small absorbent masses 4 separated from one another by a space answering the same purpose as that already described, may be fixed on said support. The resilient support 3 itself may be of an absorbent matter or not. Owing to its thinness, numerous materials may be used, provided they be resistant and resilient enough and small absorbent masses may be afiixed to them.

Figure 15 shows in a perspective view a part of a characteristic panel since the grooves like 31 are made through the whole thickness of the panel, thus forming strips .32 capable, in a sufficient degree of deformation and of absorbing a great part of thesound waves by mechanical action.

The strips .32. might be supported by crosspieces of a sufficiently deformable material or by a perforated sheet, a textile, a perforated papena perforated membrane or any other support both flexible and perforated.

In like manner, as shown in Figure 16, a panel might be made in the shape of a casing formed, for example, by a dorsal partition 14 and lateral edges l5 bounding the cup properly so called. This cup is filled with. anabsorbent material 16 and the casing is completed by a frontal partition I! exhibiting one or more of the characteristics already described. A flexible transparent sheet I8 should preferably be laid between the casing and the frontal surface I]. This sheet may be glued to the lateral edges 15, the frontal surface-11- being glued to the edges of the said sheet 18.

It is evident that by alternating and combining the different characteristics, a great numberof other forms of embodiment may be achieved.

What I claim is: 7

As an article of manufacture, a stationary non perforated sound-absorbing rectangular panel consisting of the same fibrous material throughout its entire thickness,.said panel having at least two series of substantially narrow grooves having porous sides .and fibrous bottoms and formed upon one face thereof, all of said grooves extending partly throughsaid panel, the. grooves of one series being substantially perpendicular to the grooves of the other series, alternate ones of said grooves having a depth greater than that of adjacent grooves, and a frame portion having a smooth surface and surrounding the four .sides of the panel and constituting an enclosure for said panel.

cIiAlitlfliill-l BOURGEOIS.

References Cited in the file of this patent UNITED STATES PATENTS France Jan. 4,- 1944" 

